In a conventional known bending device such as described in Patent Document 1, bending of a pipe is performed while an axial compression force is applied to the pipe, in order to avoid local thinning of a wall of the pipe upon bending.
In such a device, a chuck which holds an end of the pipe is mounted on a carriage. The carriage is moved in an axial direction of the pipe via a chain by a motor. The device is also provided with a driving cylinder that presses and moves a rack. Upon bending, the carriage and the rack are connected via a gear so that an axial compression force is applied to the pipe upon bending.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 06-182451